English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The 3D Radioastronomical Approach to Doppler tomography has been used tostudy the H$\alpha$ emission sources in U Coronae Borealis. These 3D tomogramsprovide greater resolution than the projected 2D version and highlight thejet-like gas flows in the $V_z$ direction transverse to the orbital plane. Inthis paper, the 3D tomograms are compared at two distinct epochs when U CrB wasin the disk-like state (1993 data) and the stream-like state (1994 data). Bothstates display a prominent emission source, the circumprimary bulge, which isproduced when the gas stream strikes the photosphere of the mass-gainer. Thissource is detected within $V_z$ = $\pm$150 km s{$^{-1}$}, and demonstrates thatthe bulge is not confined to the orbital plane although it achieves maximumstrength near $V_z$=0 km s{$^{-1}$}. Other emission sources include thestream-star and stream-disk shocks and a Localized Region (LR) where thecircling disk material strikes the incoming gas stream. The LR has $V_z$velocities of 200 to 500 km s{$^{-1}$} in the disk-like state. The diskemission is seen over a range of $V_z$ velocities, and there is evidence thatthe disk is inclined to the orbital plane or may have two arms. The gas streamflows along its predicted trajectory in the stream-like state, and a comparisonwith the disk-like state suggests that the gas stream has a higher density thanthe disk in both states of this binary.

Three-Dimensional Doppler Images of the Disk-like and Stream-like States of U Coronae Borealis